What antibiotic is given for bacterial sinusitis?

First-Line Antibiotic Treatment for Acute Bacterial Sinusitis

Amoxicillin is the first-line antibiotic of choice for uncomplicated acute bacterial sinusitis in situations where antimicrobial resistance is not suspected. 1, 2

Initial Antibiotic Selection

Standard First-Line Options:

• For uncomplicated cases with no risk factors for resistance:
  • Amoxicillin: 45 mg/kg/day in 2 divided doses for children; 500 mg twice daily for adults 1, 2

For High-Risk Situations:

• High-dose amoxicillin or amoxicillin-clavulanate is recommended when:
  • Patient is in a community with high prevalence of nonsusceptible S. pneumoniae (>10%) 1
  • Patient is younger than 2 years 1, 2
  • Patient attends child care 1
  • Patient has received antibiotics within the previous 4-6 weeks 1, 2
  • Dosage: 80-90 mg/kg/day of amoxicillin component in 2 divided doses (maximum 2g per dose) 1

For Penicillin-Allergic Patients:

• Alternative options include:
  • Cephalosporins: cefuroxime, cefpodoxime, cefprozil, cefdinir 1
  • Macrolides: clarithromycin, azithromycin (in cases of serious drug allergy) 1, 3
  • Fluoroquinolones: reserved for treatment failures or complications 1

Specific Antibiotic Selection Based on Sinusitis Type

Maxillary Sinusitis:

• First-line: Amoxicillin-clavulanate, 2nd and 3rd generation cephalosporins (except cefixime), or pristinamycin 1

Frontal, Ethmoidal, or Sphenoidal Sinusitis:

• These are more serious and may require:
  • Amoxicillin-clavulanate, 2nd/3rd generation cephalosporins, or
  • Fluoroquinolones active against pneumococci (levofloxacin, moxifloxacin) 1

Treatment Duration

• Standard duration is 7-10 days for most cases 1, 3
• Some specific antibiotics have demonstrated efficacy in shorter courses:
  • Cefuroxime-axetil and cefpodoxime-proxetil have shown effectiveness in 5-day regimens 1
  • Levofloxacin has FDA approval for 5-day treatment at 750mg daily 4

Management of Treatment Failures

• For partial response: Continue antibiotic treatment for another 10-14 days 1
• For poor response to initial therapy:
  • Switch to high-dose amoxicillin-clavulanate, cefuroxime, cefpodoxime, cefprozil, or cefdinir 1
  • Consider adding anaerobic coverage with clindamycin or metronidazole for sinusitis failing to improve after 21-28 days of initial treatment 1

Common Pitfalls and Caveats

• Antibiotic treatment of uncomplicated viral upper respiratory tract infections is inappropriate and strongly discouraged 1
• High-dose amoxicillin-clavulanate may cause more severe diarrhea than standard-dose therapy (15.8% vs 4.8% in one study) 5
• Recent research shows mixed results regarding benefits of high-dose vs. standard-dose amoxicillin-clavulanate, with one study showing no significant difference in efficacy 6
• Bacterial resistance patterns vary geographically; practitioners should be familiar with local patterns of antimicrobial susceptibility 1, 2
• Consider underlying factors in recurrent sinusitis cases, including allergies, immunodeficiency, and anatomical abnormalities 1

Microbiology and Resistance Considerations

• The predominant pathogens in acute bacterial sinusitis are:
  • Streptococcus pneumoniae (10-15% nonsusceptible to penicillin) 1, 2
  • Haemophilus influenzae (10-42% β-lactamase positive) 1, 2
  • Moraxella catarrhalis (nearly 100% β-lactamase positive) 1, 2, 3